A gamma-glutamyl transferase (GGT or Gamma-GT) test measures the GGT levels in the blood. GGT is an enzyme in the body, mostly found in the liver. When the liver becomes damaged, GGT leaks into the bloodstream. High GGT levels in the blood may indicate damage to the bile ducts or liver condition.
The bile ducts are the tubes that transport bile in and out of the liver. Bile is an important fluid synthesised in the liver for digestion.
The GGT test can only measure the GGT levels in the blood but doesn’t diagnose the exact cause of liver damage, so doctors order this test with other liver function tests, usually alkaline phosphatase (ALP) test. ALP is also a liver enzyme, and testing for it helps diagnose bone disorders and liver disease.
Other names include GTP, GGTP, and gamma-glutamyl transpeptidase.
A gamma-GT test helps detect bile duct or liver diseases. It is usually done with other liver tests such as bilirubin, ALP, ALT and AST tests to check if you have a bone disease, bile ducts or liver disorders. The test is also useful for monitoring or screening for alcohol use.
The normal GGT level in adults is 5 – 40U/L (units per litre). The normal GGT ranges may vary slightly among different labs. Some laboratories use different measurements or test different specimens. Consult your healthcare provider for the meaning of your test results.
Several supplements and medications can affect GGT levels, so inform your healthcare provider about any dietary supplements or drugs you take before testing. The provider may advise you to stop taking a medication before your test. Do not stop taking your medication unless your provider asks you to do so.
Small amounts of alcohol can also increase GGT levels, so your healthcare provider may recommend avoiding the intake of alcohol at least 24 hours before the test.
A blood test, including the GGT test, involves the following.
This procedure usually lasts less than five minutes.
After a healthcare provider collects your blood sample, they will send it to the lab for analysis. When your test results are ready, your doctor will share them with you.
Blood tests are quite common and important in medical screening and testing. Blood tests have very few risks. These include bruising or slight tenderness at the site of the blood draw, but they resolve quickly.
The test results are usually available within 1 – business days but can take longer.
The normal GGT range differs in laboratories, but the common reference range for adults is 5 – 40 U/L (units per litre). Since the ranges vary depending on the lab, ensure you check your test result for your lab’s specific reference range.
Generally, GGT levels are slightly higher in people assigned male at birth and men than in people assigned female at birth and women. Also, GGT levels usually increase with age in people assigned female at birth and women but don’t in people assigned male at birth and men.
If you have a normal or low GGT test result, you are unlikely to have consumed any alcohol or have liver disease.
The results of GGT will be international units per litre or IU/L. The normal GGT level for adults ranges from 0 – 30 IU/L. Values above 30 IU/L may indicate liver disease or condition.
Several liver diseases can cause elevated GGT levels. They include:
However, only elevated GGT levels aren’t sufficient for the doctor to diagnose liver disease. For example, doctors usually recommend other tests, such as alkaline phosphatase (ALP) testing. ALP is an enzyme that accumulates in the blood if the liver isn’t functioning properly.
A higher-than-normal GGT level in the blood can indicate a disease or condition is damaging the liver. However, only a GGT test cannot determine the exact cause of the liver damage. Generally, the higher the GGT level, the more damage to the liver.
Liver conditions that can increase GGT levels include:
Other conditions that can cause increased GGT levels include:
A high GGT level doesn’t always indicate a medical condition that requires treatment. Other factors that may affect your GGT levels include:
Even a small intake of alcohol within 24 hours of a GGT test can elevate your GGT levels. However, those who frequently drink lots of alcohol usually have higher GGT levels than people who drink heavily occasionally or take less than 2 – 3 drinks daily.
Smoking cigarettes usually causes higher levels of ALP and GGT.
Some medications can increase the level of GGT. These include phenobarbital, carbamazepine, acetaminophen and phenytoin.
In addition to these factors, your doctor will also consider your situation and different aspects of your health while analysing your GGT result. These include:
If you experience symptoms of liver damage like belly pain or jaundice, consult your healthcare provider. Ensure you also consult your healthcare provider if you previously had a liver condition diagnosed and are currently experiencing concerning symptoms.
You should also consult your healthcare provider if you think you have an alcohol problem, as they can help create a treatment plan and offer referrals to a support program.
If you experience liver disease or condition symptoms, contact Blood London at 020 71830244 to book an appointment for a GGT test and other appropriate tests. You can also call us for more information on the Gamma-GT test.
Select the test that you would like to undergo
Go to the Harley Street clinic for your blood draw and pay for your test in person
As soon as the results are ready, the will be sent to you by your chosen method
